title: Differentiating syndrome X from coronary artery disease by treadmill exercise test in patients with chest pain and exercise-induced myocardial ischemia.
abstract: Even though the underlying mechanisms of myocardial ischemia may be different, it is difficult to differentiate syndrome X from coronary artery disease (CAD) by means of the treadmill exercise test in elderly patients with chest pain and exercise-induced myocardial ischemia. One hundred sex- and age-matched patients-42 with syndrome X and 58 with CAD-were studied. Another 10 subjects with atypical chest pain, negative treadmill exercise test, and normal-appearing coronary angiograms served as controls. We evaluated the difference in exercise performance between patients with syndrome X and CAD, and the treadmill exercise test was undertaken with modified Bruce protocol within 2 weeks before coronary angiography. Parameters including time to 1 mm ST segment depression (STD), exercise duration (ED), heart rate (HR), systolic blood pressure, rate-pressure product (RPP), and percentage of age-predicted maximum HR (% HR) at different stages of the test were measured and then compared among the three groups of patients. Compared with CAD patients, syndrome X patients had significantly higher HR, % HR, and RPP at the time of 1 mm STD and at peak exercise. The time to 1 mm STD and ED were longer in syndrome X than in CAD patients. However, ED was shorter and HR, % HR, and RPP at peak exercise were similar in syndrome X patients as compared with control subjects. The new criterion of combined ED (> or =315 seconds) and RPP at peak exercise (> or =24,000 beats x mmHg/min) was found to be highly specific (86%) and moderately sensitive (64%) in differentiating syndrome X from CAD patients. The positive likelihood ratio for this criterion was 4.57 and negative likelihood ratio was 0.42. In conclusion, syndrome X patients had better exercise performance than CAD patients, but less ED and similar workload when compared with control subjects. The new criterion proposed in this study may provide a quick and simple way to differentiate syndrome X from CAD in a group of aged and predominantly male patients with chest pain and positive treadmill exercise test.
authors.affiliation: Department of Medicine, Veterans General Hospital-Taipei, and School of Medicine, National Yang-Ming University, Taiwan, ROC.
authors.forename: N W
authors.initials: NW
authors.lastname: Hsu
authors.forename: J W
authors.initials: JW
authors.lastname: Chen
authors.forename: S L
authors.initials: SL
authors.lastname: Jen
authors.forename: B I
authors.initials: BI
authors.lastname: Kuo
authors.forename: W L
authors.initials: WL
authors.lastname: Lee
authors.forename: G Y
authors.initials: GY
authors.lastname: Mar
authors.forename: S J
authors.initials: SJ
authors.lastname: Lin
authors.forename: S P
authors.initials: SP
authors.lastname: Wang
authors.forename: M S
authors.initials: MS
authors.lastname: Chang
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000787:Angina Pectoris / Q000175:diagnosis*; D001794:Blood Pressure / Q000502:physiology; D016022:Case-Control Studies; D017023:Coronary Angiography; D003327:Coronary Disease / Q000175:diagnosis* / Q000503:physiopathology; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005080:Exercise Test / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D017566:Microvascular Angina / Q000175:diagnosis* / Q000503:physiopathology; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012737:Sex Factors; D013599:Systole; D013997:Time Factors